¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. HP8924-Family-Spectrum-Analyzers
  2. Topics

8935 no power up

 

My 8935 was working fine. Passes all tests. It was powered up on my bench and suddenly shut down. It will not power up. The GFI is not tripped. If I turn on the power switch the unlock led blinks and there is a click in the speaker, this repeats over and over.

I am guessing there is a power supply problem.

Any suggestions here before I dig into it?

Thanks

Rik Rasmussen
 

Hi Rik,? I guess the problem will be on the rear most power supply board. Not sure what it is. Rick

On May 15, 2023 3:22 PM, Rik Rasmussen <rikrasmussen@...> wrote:
My 8935 was working fine. Passes all tests. It was powered up on my bench and suddenly shut down. It will not power up. The GFI is not tripped. If I turn on the power switch the unlock led blinks and there is a click in the speaker, this repeats over and over.

I am guessing there is a power supply problem.

Any suggestions here before I dig into it?

Thanks

Rik Rasmussen

 

Appears to be a switching power supply, with a regulator board mounted above it. It seems the switching?power?supply is not starting up. Not even the fan runs.

_____________
Rik Rasmussen



On Mon, May 15, 2023 at 10:17?PM rab@... <rab@...> wrote:
Hi Rik,? I guess the problem will be on the rear most power supply board. Not sure what it is. Rick

On May 15, 2023 3:22 PM, Rik Rasmussen <rikrasmussen@...> wrote:
My 8935 was working fine. Passes all tests. It was powered up on my bench and suddenly shut down. It will not power up. The GFI is not tripped. If I turn on the power switch the unlock led blinks and there is a click in the speaker, this repeats over and over.

I am guessing there is a power supply problem.

Any suggestions here before I dig into it?

Thanks

Rik Rasmussen

 

¿ªÔÆÌåÓý

Right,

? I would check the 47uF on the "daughter " board first. See attached picture. Rick

On 5/16/2023 10:47 AM, Rik Rasmussen wrote:

Appears to be a switching power supply, with a regulator board mounted above it. It seems the switching?power?supply is not starting up. Not even the fan runs.

_____________
Rik Rasmussen



On Mon, May 15, 2023 at 10:17?PM rab@... <rab@...> wrote:
Hi Rik,? I guess the problem will be on the rear most power supply board. Not sure what it is. Rick

On May 15, 2023 3:22 PM, Rik Rasmussen <rikrasmussen@...> wrote:
My 8935 was working fine. Passes all tests. It was powered up on my bench and suddenly shut down. It will not power up. The GFI is not tripped. If I turn on the power switch the unlock led blinks and there is a click in the speaker, this repeats over and over.

I am guessing there is a power supply problem.

Any suggestions here before I dig into it?

Thanks

Rik Rasmussen

DSC07840_LI.jpg

 

That is how my E8285A was acting just before it got to the point that nothing at all happened when I pushed the power switch. Replacing all of the electrolytic capacitors and one tantalum capacitor on the main power supply board fixed it. About a year ago, sourcing the parts was a frustrating process. I manged to get them all from Digi-Key but had to settle for second or third choice on some due to stock status, and had to order one from a third party supplier through Digi-Key community with a separate shipping charge. I replaced both batteries while I had it open.

Paul
 

Thanks will try that first!
 

Any chance you could copy/paste that list of components you ended up using here?

Thanks for the info.

Rik
WA4BAN
 

Hi! I am new to this site.

Joined because my 8935 just wouldn't power up one day. I did not have it plugged in or turned on for several months, and when I went to use it, it was dead. Would not turn on at all.? I eventually found this site and read about the 47uf 50 volt cap on a little stand up board on the main power supply board. I found two 47uf 50v caps on different little standup boards and replaced both of them because I was in there and because I did not know which one was the culprit. I had very little faith that this would actually fix my 8935, but it was the only thing to try because a long search for schematics turned up empty and I was flying blind. I was able to replace both caps without removing the stand up boards. It was a bit tedious but went well. One of the caps I mounted on the back side of the board because it was easier to do. Anyway, bottom line it it worked! I couldn't believe it! I am so happy! if I had not found this group I would not have known what to do.

Thank you! Thank you!

Chris Bolkan
 

Chris,

You're welcome.

Thank you so much for telling your success story.? By doing that you gave back to the group as a whole and to the specific members who were involved in that thread.? Rick made the specific suggestion about that exact cap -- even posting a picture of it!

Besides giving everyone a lift, there was a not insignificant technical component to your posting in that you provided evidence that this simple recapping (as opposed to an "extreme makeover" style 100% recapping) worked again.

You're replying to a thread from May 2023 for the benefit of members reading by email:


Hank

1 - 9 of 9